It is well known that biological materials fluoresce when irradiated with light in the ultraviolet region. In general, the excitation light has a wavelength from about 260 to 360 nm. The emission from the biological materials can be anywhere from the excitation wavelength (scattered) to the visible range. Many particle detectors for detecting biological agent aerosols, e.g., the Tier-3 Biological Aerosol Warning System, are based on this phenomenon.
Historically, these particle detectors use a laser for the excitation process. One or more photon detectors, or photo multipliers, are used to capture emission from the sample particles and scattering. Many particle detectors also employ a flow-through design, where the sampled particles pass through the excitation light at a relatively fast pace. This is done to improve the sampling statistics. However, these particle detectors are often undesirably large, heavy, and expensive and consume undesirable amounts of power for many applications, such as field applications, e.g., particle detectors for use with military ground forces, on moving ground and air platforms, within structures, etc.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for alternative particle detectors for detecting biological agent aerosols.